This week the team finished up some taping, Gutex, and house wrap to prepare for strapping and siding.

Now that the electrical rough-in is finished, there are quite a few spots where wires are protruding from the interior to the exterior of the house. This is necessary for mechanical systems such as the HRV, sill-cock penetration, ASHP line set penetration, and and some exterior lighting and duplex connections; all which require creating penetrations in the process. Before we finished up the rest of our Gutex panels, some members of the team spent the first half of the day detailing and taping these penetrations which returned the house to an airtight enclosure.

Simultaneously, some other team members followed the tapers to fill in some of the gaps in our Gutex layer. Ever since the Gutex arrived on site it has been a star studded material. Nobody including the instructors have worked with the material before so everyone has been curious about its characteristics and installation process. I have found it is easy to cut (especially with a table saw), it is light enough for one person to handle, it does not cut you up like fiber glass or other insulations, and it can be fully exposed to rain without affecting its performance. It will be interesting to see how this material stands up to the test of time, if you want to learn more about the material, the experts at 475 High performance Building Supply dive deeper into the subject. However, if a section of Gutex needs to be taken out and replaced, it can be a challenging process. Each piece is made of wood fiber so when trying to rip one piece out, it creates a lot of friction. Removing a piece of Gutex often results in big tears, so it is ideal to install it correctly the first time. In addition, Gutex is tongue and grooved on all sides in order to create a continuous thermal layer, so removing a section creates a noncontinuous joint of insulation. In order to fix this problem, the crew has been using Visconn (a liquid applied air barrier) donated by 475 High performance Building Supply which when used correctly returns the insulation to a continuous layer. Even a small crack in our thermal barrier will affect the energy use of this house so it is important to leave no stone unturned.

Finally, we finished the day with another layer of Weather Resistant Barrier (WRB) over the Gutex. Like the other WRB, this layer will wrap under the house and attach to the Zip System Insulation Board beneath the floor joists. The House Wrap will easily staple to the Zip System Insulation Board and be detailed with Tescon Vanna tape to compete the air barrier, but we found that the WRB does not staple well to Gutex. The wood fiber is hard to the touch, but is not dense enough to hold staples. The staples will hold for a little while, but a brisk wind will rip off the Gutex without hesitation. We found that a few strips of tape around the perimeter of the WRB remedied the issue.

The strapping for our siding will be installed next weekend and will create a strong connection between the WRB and Gutex. In addition, we hope to get well into siding on the following weekend! Then cellulose insulation, Intello, Dry Wall and before you know it, trim, cabinets and countertops will be installed along with finish flooring and painting. The HyggeHaus is almost ready for the Green River Festival, so make sure to stay tuned for the last few weeks of the Build!

Hello longtime readers and new readers of the HyggeHaus blog! Yes, you! The Building and Construction Technology (BCT) Program is asking for your help during UMassGives to raise funds for the Design-Build Program that has made this semesters build possible. If you are a first time reader, feel free to check out the the work we have completed so far in the posts below.

This project is a collaboration between BCT, Architecture, Five College Architectural Studies Program, and East Branch Studio, with L. Carl Fiocchi leading it from our program’s side. I would also like to give a shoutout to our sponsors 475 High Performance Building Supply, Eco Buildings Bargain, Graham Electric, and John Thomas Plumbing and Heating for their outstanding support.

Our team has been busy building the first of what will hopefully be many dwellings that – after completion – will be made available to affordable housing associations and others. For students, this offers an amazing hands-on opportunity to learn about the various aspects of high-performance buildings and construction. Specifically, it teaches about construction practices, low load mechanical systems selection and installation, performance verification, and carbon accounting. I am a senior in the BCT major at UMass Amherst who has had the pleasure of participating in this project, in addition to writing the blog alongside coauthor Lia Douillet. This has hands down been the best academic experience I have experienced in my four years here. The BCT courses I have under my belt are enlightening as is, but the opportunity to apply this knowledge in the field is something I would recommend to all my peers. The whole team has enjoyed witnessing the fruits of our labor ripen, and it will only get better throughout the years.

We are hoping to raise funds during UMassGives in order to support this project for future years. Gifts from our community of alumni, friends, faculty, parents, staff, and students will help us get there! 

Please join us in this important effort and inspire the generosity of others by sharing on social media! Thank you!

Learn more about what we do in BCT: https://bct.eco.umass.edu/ and stay tuned with our blog to see the completion of the HyggeHaus in the next couple months!

On Friday, April 22, the Hygge House reached another major milestone: the completion of rough electrical work! Thanks to the technical expertise of Graham Electric of Haydenville, MA (with an assist from the DesignBuild student team), the house is one step closer to being equipped with all the comforts and conveniences of home. Yes, you can do a lot in terms of heating, cooling and lighting with passive strategies…but not everything! A system of wiring for distributing electricity to power appliances, HVAC equipment and lighting fixtures is essential for a modern house, and that is the focus of the rough electrical install phase.

Preparing for this phase requires a few per-requisites: first, all exterior framing and wall and roof sheathing must be complete; ideally, the house should be fully “dried in” with all windows and doors installed (we’ve decided to hold off on door installation to maintain easy access to the space so we can use it to store tools and materials, and to avoid potential damage to the glass doors.) Second, all interior walls which will contain wiring must be framed for this phase to proceed. The rough electrical work covers pulling wiring, mounting junction boxes for outlets and controls, and installation of the electrical panel (aka breaker box), grounding, and overhead service wire. It doesn’t include the installation of switches, outlets, or fixtures yet-that will happen after insulation and drywall! (So for now, our power supply is still dependent on extension cords.)
In this phase, it’s important to keep everything neat and labeled and to avoid kinking wires or damaging insulation on wires. Metal plates are installed over studs where wires run through them to prevent damage from stray fasteners during the finish phase.

The rest of the weekend featured more Gutex installation and detailing. We used Visconn, a liquid-applied air barrier product, to seal the Gutex at the corners of the building. Visconn was also applied around the windows to provide an application surface for tape and for further air sealing. One more piece of exciting news from this weekend’s build: We got to enjoy a rare day of warm, sunny weather!

This build weekend began with another significant milestone: window installation! Our 5 donated windows are a mix of flanged and nonflanged. These types of windows require different types of installation detailing. Flanged windows have (as the name suggests) an integrated nailing flange that runs all the way around the perimeter. When the window is installed, the back of this flange sits against the outside face of the sheathing. Nonflanged windows are attached to the window rough opening by nailing tabs integrated into their frames. Apart from this difference, the installation process for both window types is similar: first, the window opening is lined with a window buck made from ZipSystem sheathing, which is taped with Tescon Vana tape in the corners and around the intersection with the outside face of the sheathing for air sealing. Then, a piece of clapboard siding is nailed in the opening and covered with a layer of Extoseal Encors stretch tape to create a waterproof, slightly pitched sill pan. The tape is lapped over the edge of the window buck and sealed to the outside of the sheathing over the house wrap (for flanged windows) or outboard insulation (for nonflanged windows). This sill pan will drain out any water that may leak into the window, protecting the wall assembly. Another layer of Extoseal goes over the top of the window buck for additional protection from water. The window is then moved into place and centered in the rough opening. Next up is leveling, plumbing and squaring the window. After an initial check with a level, one corner (on the high side of the window) is tacked in place. Composite shims are inserted under the sill to level the window out, and the tab or flange in the opposite corner is nailed off. Next, the window is checked for plumb with a level, and checked for square by comparing diagonal measurements between opposite corners. Any necessary corrections are made by using a small flat bar to pry the window into place before it is fully nailed off. Flanged windows require a few additional details: a bead of acoustic sealant is applied to the back of the flange before install for air sealing, and after it’s nailed in place, the flange is taped over with Vana tape on the sides and top for air sealing and bulk water protection. A buck constructed from 2×4 rips is built around the window to provide a solid surface to butt the outboard insulation up to.

Flanged windows are the most common type used in American residential construction, but they have one major drawback: the nailing flange has to be nailed to the wall sheathing, restricting where they can be set relative to the depth of the wall assembly. This also means that the installation of the flanged windows must be completed before outboard insulation can be installed around them. For the nonflanged windows, on the other hand, the outboard insulation can be installed around the prepared rough openings with their ZipSystem window bucks before the windows are in place.

This created a fork in our critical path. While one team of students worked on window install, another team unwrapped the pallets of Gutex Multitherm that had been waiting under a giant tarp for the past few weeks. Gutex is an innovative insulation product made from wood fiber treated with paraffin to repel water. It has an R-value of 3.6 per inch of thickness; we used the 80mm (~3 1/8″) variety, contributing an R-value of 11.4 to our wall, and eliminating the thermal bridging effect of the wall framing. Gutex comes in board/sheet form similar to XPS, EPS or polyiso foam insulation and can be cut to size and attached with fasteners in the same way these products can. Unlike foam board insulation, it’s made from renewable resources and without CFCs or other environmentally damaging blowing agents. However, working with Gutex is not without its challenges. It’s approximately 3″ thick, which is greater than the maximum cut depth of a standard circular saw blade, and substantial enough that cutting it with hand tools is slow going. Our answer to this was to use a combination of tools: our trusty SawStop table saw for long rip cuts, and a jigsaw with a 6″ blade for shorter cuts and notches with square corners (for fitting around windows and doors.) It has tongue-and-groove edges to lock neighboring sheets of insulation together and prevent gapping, which is great from a performance standpoint but does require pieces to be installed in a specific orientation, limiting reuse opportunities for cutoffs. Not only do pieces need to be oriented correctly, the joints must be staggered between courses-and we also had to remember the 5″ wide removable strip of Gutex that covers the joint between building sections! Since Gutex is a European product, the sheet dimensions were based on the metric system, rather than corresponding to the standard multiples of inches and feet that American-made building products are based on. With all these installation constraints, the pile of scrap grew quickly. And so did the fluffy drifts of wood fiber produced from cutting the Gutex (which, in my experience, is still far preferable to the irritating by-products of working with rock wool or foam board!) The Gutex team made short work of installation, and by the end of the day the entire back wall and portions of the side walls were covered.

This rainy Saturday was the perfect day to stay inside and learn about plumbing from the experts at John Thomas Plumbing and Heating. To start the day off, their team led us through the steps of plumbing installs, including Pressurized Lines, Waste Lines, and Venting, plus a Ductless Mini-Split Heat Pump installation. A bonus was a demonstration and hands on opportunity for sweating copper piping and fittings.

At the copper soldering station, students took turns testing their skills with a torch, flux, and solder. The first step to forming a leak proof copper pipe connection is a clean surface where the copper pipe and fitting will connect. Any type of sandpaper can be used to abraid the outside surface of the pipe and inside the fitting where the pipe will be inserted. Next, flux is applied to the outside of the copper pipe and inside the copper fixture. Flux is essential in this process as it emulsifies oil on the copper, allowing the acidic chemicals in the flux to lift dirt and oxides off the surface. If any oxides are left they would corrode the copper pipe leaving small leaks (or worse) which can lead to mold build up in cavities, structural deterioration, or associated flooding issues. Then, with the help of a torch, the solder is brushed along the copper connection and “sucked” (capillarity) into the joint creating a leakproof connection. Last but certainly not least, the finished connection must be wiped with a rag to remove excess flux which can also corrode copper if left for too long.

While students improved their soldering, another group observed the layout for the Ductless Mini-Split Heat Pump which will eventually live on the East wall of the HyggeHaus. Back in 2020, the design team chose this unit as our main source of heating and cooling because of its high Coefficient of Performance (COP). COP is equal to the power output divided by the power input of a unit and represents the efficiency of HVAC systems. For instance, our Ductless Mini-Split Heat Pump has a COP of 4 meaning it will produce 4 kW of energy for every 1 kW of energy used. This is a substantial improvement compared to electric furnaces or baseboard heaters which have a COP of 1. Another reason the 2020 team chose this unit is because it would have efficiently utilized the energy produced by the Photovoltaic System planned for the roof. As mentioned in previous posts, the HyggeHaus will not be able to host Photovoltaics due to a lack of direct sunlight at its final destination. Regardless, a Ductless Mini-Split Heat Pump will be cost effective, and more indoor units can easily be added if needed. The unit will not be installed until the latter portion of the build, but the piping (lineset) for refrigerant and condensate drain line are now waiting patiently in the wall to be utilized. The condensate drain will direct water into a 50 gallon rain barrel that will sit outside the house. We estimate the condensate from the mini-split will produce enough water to fill up the rain barrel about every 2 weeks when the unit is running 24/7. By storing this condensate for later use, the HyggeHaus occupants will be able to water their plants, wash off their bikes, or have water balloon fights without increasing their water intake.

To finalize our day of plumbing and HVAC, another group installed hot and cold water lines for the sinks and shower which were wrapped in pipe insulation to reduce heat transfer. This was accompanied by a waste lines and venting. Undoubtedly the most fearless and noble member of a house, the waste pipe carries your undesirables from the toilet to the septic tank or municipal sewer along with grey water from showers and sinks. Despite the waste pipes heroic role in a house, the plumbing system would not be possible without the vent stack which regulates air flow throughout the system.

The next day consisted of priming the tongue and groove siding which will make up the facade for the HyggeHaus.